Use of product gases in a fluidized conversion process



NET GAS PRODUCTION Nov. 4, 1958 M. R. SMITH 2,859,175

USE OF PRODUCT GASES IN A FLUIDIZED -CONVIIRSON PROCESS Filed NOV. 16, 1954 a Ln Eug@ g m 1 cu m o no.

.n s: n', T )VY m .9) k( c: Y O f c N l Q '2. N

E Q 9 3 l l l l l 1 :9)

| "I l f .L I l l l l ln 2 N zo N no i" I T 1.,. n. o 'ill' I .7 I I'l.. E* IT l" l 9| D m 1 d YI' 40|; I I :I o 5 9 INVENTOR.

MARTIN R. SMITH Hyg/44m ATTORNEYS United States Patent Ofi ice USE OF PRODUCT GASES IN A FLUIDIZED CONVERSION PROCESS Martin R. Smith, Glen Ridge, N. J., lassignor to The M. W. Kellogg Company, Jersey City, N. J., a corporation of Delaware Application November 16, 1954, Serial No. 469,255

3 Claims. (Cl. 208-436) This invention relates to an improved method of recovering entrained catalyst fines from a'vaporous reaction product of a hydrocarbon conversion process. More particularly, it relates to a method of recovering entrained catalyst lines from the Vreaction' product of` a hydroforming reaction. Still more particularly, it relates to an improved method of returning such nes to the reaction zone as -an oil slurry. Y

In hydroforming, as in other fluidized hydrocarbon conversion reactions, a major problem exists with regard to catalyst recovery. yEven though separation is carried out in a settling zone and by means of cyclone separators, a certain amount of catalyst nes invariably escape from thereactor with the vaporous reaction products. Recovery of these entrained catalyst nes becomes a matter of economic importance in large scale operations and various means have been proposed previously for their recovery. One of the most frequently used methods involves returningy catalyst iines Ato the reactor as an oil slurry. The oil used to form this catalyst slurry may be obtained from an external source or may be part of the feed or reaction products. For various reasons, such methods have not been entirely satisfactory.

Vaporous reaction products of hydroforming reactions include normally gaseous material, gasoline, polymer and entrained catalyst particles. It has been the custom in the past to pass the reaction product to a fractionator where liquid polymer is separated from gasoline and normally gaseous products. The polymer is then used, in the same tower, to scrub entrained catalyst particles from the other reaction products. Polymer and catalyst fines are withdrawn from the fractionation zone and introduced into a settling zone where catalyst fines settle as a slurry and supernatant liquid polymer is drawn ott. The slurry of catalyst lines is .then returned to the reactionzone by means of a mechanical pump.

There are several serious disadvantages to this method of recovering catalyst lines. One of these disadvantages is that there is a strong tendency for catalyst fines to settle from the slurry in the transfer line to the reactor. If left unchecked, this tendency would soon result in complete plugging of the slurry transfer line. To avoid this eventuality, past practice has dictated the use of larger amounts of oil vehicle than would be otherwise desirable. The use of excessive amounts of oil vehicle, while alleviating the problem of catalyst settling in the transfer line produces other undesirable results, all of which areV attributed to the greater amount of reactor eluent produced by the extra oil vehicle. The most immediateeffect of a greater amount of reactor euent is an increase in the amount of catalyst entrainment. The additional catalyst thus entrained places an extra burden on the cyclone separators and aggravates the original problem of catalyst lines recovery. An'increased amount n returning them to the reactor which substantially alleviates these disadvantages.

It is an object of this invention to provide an improved method of recovering entrained catalyst lines fromthe reaction product of hydrocarbon conversion processes.

Another object of this invention is to provide an improved method of recovering entrained catalyst nes from the reaction product of a uid hydroforming process.

A further object of this invention is to provide an improved method of recovering entrained catalyst ines from the reaction product of a uid hydroforming process and returning them to the reaction zone as an oil slurry.

Other objects and advantages will become apparent from the following explanation and description of my invention.

By means of my invention, it is contemplated to recover catalyst fines entrained in the reaction product of a hydrocarbon conversion process as van oil slurry and to inject a normally gaseous material into said slurry to" liquid product, separating normally gaseous material from the reaction product, forming a slurry of nes in high boiling liquid product and recycling the oil .slurry thus formedvto the conversion zone by injecting at least a portion of normally gaseous material into said slurry and passing the same through a transfer zone leading to the conversion zone.

The present invention is applicable to any hydrocarbon conversion process in which particles of catalyst entrained in the reactor effluent are recovered and returned to the reactor as an oil slurry. While it can be utilized in such processes as reforming, dehydrogenation, hydrogenation, desulfurzation, catalytic cracking, isomerization, etc., myV invention is particularly applicable to the hydroforming y process. `In hydroforming processes a polymer boiling above the gasoline range is produced which can be used to scrub the catalyst lines from the vaporous reaction product and then readily used as the oil vehicle for rcturning the slurry of recovered catalyst lines to the reaction zone. The hydroforming process also produces an excess of normally gaseous product containing hydrogen and light hydrocarbons which can be utilized in the transfer of catalyst slurry in accordance with the invention.

While the oil vehicle and the gaseous material used in the return of recovered lines to the reaction zone can be derived from the process employing the same, it is also intended to make use of other suitable oil Vvehicle and normally gaseous material. The oil vehicle used in the slurry transfer line can, for example, be any high boiling hydrocarbon oil which is liquid at the conditions of temperature and pressure to be found in the slurry vtransfer line.

Further, the gaseous material to be injected into the slurry can be any material which is gaseous at the conditions of temperature and pressure to be found in the slurry transfer line, and it can be for example, flue gas, steam, carbon dioxide, etc. Product gas of the hydrocarbon conversion process which contains normally gaseous hydrocarbons and hydrogen is particu-` larly suitable yfor injectioninto the catalyst slurry.

In the hydroforming process alight hydrocarbon oil,

e. g., gasoline or naphtha, is contacted with a dense bed.

of nely divided reforming material under conditions suitable for producing a product of high anti-knock Patented Nov. 4, 1958 quality,,lha-concentration o'fdnely divided solid material entrained -in ,the gaseous material usually varies from about 0.1 to 100 grains, more usually about 0.5 to 15 grains of solids per cubic footof gaseous material. The

hydroforminggprocess is- ,carried; ou t at,a Vtemperaturerof about 750 to about 1050 F., more,.usually about .850.torw

aboutffQSOrF. andra pressureof aboutZS, to about 31000 p. s.. i. g.,. moreusuallyfabout 50to about=g500;p.1s. i. g. The total pressure of the reaction is maintainedforythe,n

purpose lof -providing a hydrogen par-,tial pressurewhiclt is advantageousfor suppressing carbon ancolie formation. i The hydrogen-supplied tofthe .reformingzone is from 1 about- 500 rto about\ 20,0.00 standardl cubic :feet ;(measured at 602712., -and\760 mm. Hgtpressureyper. barrel, rabl n:e.` viated as-s. c. .f, b., more usually; about,-.1000 to about; 7500 s. c. f. b. Thequantity of oil being processed-relativetpathe quantity of catalyst whichHis presentinrthe' reationrrzone is ,designatedlin terms ofthe weightyspacef; velocity, which is measured as the pounds of oil feed on an v hourly.basisper -pound of catalyst which is presentV f in the reaction Zone. The weight `space velocity `varies from about .05 `tofabout 10 lb./hr./lb. morefusually about, 0.1 to about 2.5 lb./)hr./lb. The process can beoperated as either `-a fixed or moving bed system-using-iluidized catalyst... In the moving bed system -.the relative v vei-ght` of catalyst beingcirculated to oil charge is Ameasured Ona weightgbasisand, generally, it can be about 05E-,to

about-.15, usually labout 0.14 to about 2.0. Usually, ther.y

processjs operatedunder such conditions that there s a net ,production.ofhydrogen .and there is no .needto use an extraneous ,source of. hydrogen to maintain the Y process.

Any suitable reformingcatalyst can be used in-the process. Catalysts having aromatizaton or dehydro genation-hydrogenation properties, for example,.arefsuitable. Examples,of .cataly,sts which can be used for thisvpurpose arecornpounds of, metals in groups V and VI of the.l

periodic tab1e;more particularly, the oxides and/or suldes,of the gleft-hand elements of groups V and VI of the periodic table'. Another suitable class of catalyst is thenoble metals of group VIII of the periodic table, suchasrplatinum and palladium. The heteropoly acids, suchas. those` containin-g the elements molybdenum,

tungstemwanadium and chromium, can also be used. for

thispurpOSe. Examples of the heteropoly acidsare bauxite, zine alrninate, Superltrol, kieselguhr, purnice, j

etc. The catalyticelement usually comprises about 0.01

to about 25%'of the total catalyst, on a weight basis:

As previously indicated, in uid hydroforming, there. f action product comprises Vnormally gaseous product, gas-A oline and polymer- The gasoline product is normally a f liquid `which has aninitial boiling point of about,85to.

about 175 F. and an end pointof about 350`to about.

450,7` F., more usually an `end point of about 400l to .425?

F. 'The polymer. is normally' liquid and `of a higher boilinghrange thanthe gasoline. ,Since the polymercontai-ns a highyconcentration of aromatics of a highly refractive nature. it serves unusually well as a vehicle fof recycling. recovered catalyst fines to the reaction zone. The poly mer is also used to quench the vaporous reaction product containing'theentrained catalyst nes. The-fpolymencan.

be used for Ythis purpose many times without danger of Y becoming decomposed andcontaminatingthe gasoline product ,Quenching takes place in 'a suitable quenching zone or tolverlcontaining internal baies over Which polymer vilows, downwardly in countercurrent vcontact. -with r the upflowing vaporous reaction product. .The tower containing'thenscrubbing rnone also-maycontaina fractionf ation ,.zone, kfor the. separation of the polymer from fthe;

lighter boiling `normallyj liquid product material Scrubf.

bing the vaporous Vreaction product yvith polymer result-s` 4 in wetting of the entrained catalyst particles and in condensation of vaporous polymer vc :ontainediuthe `rea c :t i or1 product.

A mixture of polymer and catalyst fines is Withdrawn from the scrubbing zone and further processed for separation of catalyst iines. In this regard, the mixture of polymer and catalyst nesis passed to a separation zone, e. g., a settling z one where the catalyst fines are allowed to settle Yto form a slurry anda liquid po,lyrr1e1of\substantially reduced nes content is produced. Slurry is withdrawn from .the separation zone and-returnedfto.thee 1 reaction rzone. The density of v catalystin-.they-slurry which is returned to the reaction zone can be expressed in terms of pounds of catalyst per gallon of oil vehicle. Y As mentioned previously, past practice has necessitated the use of relatively-large quantities.ofoilvehicle in order to alleviate the tendency of the catalyst nes to settle out in the transfer line. The practice in the past has been to use a slurryl comprising` fromab o ut0..5:l lton1.0..lb:lof catalyst per gallon of oil vehicle. In accordancegwiththefz.. present invention, a portion of the normally gaseous prod-1.

uct from the hydroforrningprocess isinjectedinto they" slurry to assist in returning the slurry tothe reaction zone. The amount of gas lso injected can vary Widely i. c .,inf general, about 0.5 to about 10, 4and preferably fromabout 2 to about 5 s. c. f. (standardl cubic feetmeasuredat 60% F. and 760mm. Hg)` per lb. of slurry. Injectinggaseous material in this manner-allows theuse of relativelylessffr.

oil vehicle in the-slurry without danger `ofcatalyst'se tling. In general, it is possible,-with injectionofgaseou material into theslurry, to operate successfully with recycleA s lurry, can. befurther reducedby .a pressure the Vseparation or settlingzonesubstantially above, .th pressure in the reaction zone..V A substantiallyhigh pressure in 4the separationor settlingzonethan inrth reaction `zonewillassist in returning slurryto the reacf. tion zone, and further, sucha pressure dierentialgwill, allow the,use ofvhigher:concentrations ofvcatalyst in ,th slurry without .undue settling of catalyst lines. Thems of pressure dilerentialalone for this purpose, hovv e V-e :r,y l

hasserious disadyantagesfwhich are not. present in f th practice of my invention.,; Inthe-case ofpressuring slurry tothe reaction zonewithout the use of gas injecf tion, serious erosion-occurs at thepoint where the pressure is reduced. In order vto preventsettling ofcatalyst nes by the presentinvention, the linear velocity ofthe... slurry is maintained at a minimum value depending-on f; the concentration of catalyst nesin the slurry. Ifthe linear velocity becomes too low forV a givenslurry con-.,,..l

centration, settlingjof catalyst lfinies-willy occur higher` the concentration of catalyst iinesin the material-- passing through thetransferzoneor line, thehigherw' be the linearvelocity neededto preventsettling.: V,The/net,... i

eiect of injecting gaseousrmaterialjnto the slurry isfto'.` lowerthe concentration of catalyst in the material pass ing throughthe transferzone or line, and thus reduc the tendency for settling. The use of a substantial, pressure diierential will operate .to reduce the vamountoff gas material injected, but it is undesirable to relysolely" on pressure diierential because theadvantage.of,the; present invention resides in substitutinglgaseous ,material for Vliquid and no t in merely'eiecting4 an,. incr.e as e. linear (eloci ty. l Ahighpressure differentialismdesir able, because the resulting pressure drop across the required pressure reducing valve in the transfer zone orv separation zone causes severe erosion and necessitates frequent replacement of this equipment. As a practical matter, it has been found that, generally, a pressure differential of not more than about 50 p. s. i. is desirable from the standpoint of erosion, `more usually about 15 to 35 p. s. i. A further disadvantage in using high pressure differentials alone for the purpose intended lies in the size of pipe required for the transfer. Higher velocities require smaller sizes of pipe for the transfer of equal amounts of slurry. Since the amount of catalyst lines being returned is usually small, high pressure dierentials may result in the necessity of using pipe of an impractically small internal diameter. In addition, the problem of catalyst settling would be aggravated by extremely small pipes since such pipes would plug more readily than larger ones. In accordance with this invention, the gaseous material is injected into the transfer line or zone containing slurry in an amount to provide a superficial linear velocity of about l to 50 feet per second, more usually about 15 to 30 feet per second.

From the foregoing, it should be apparent that injection of gaseous material into the slurry in accordance with my invention will reduce the pressure needed in the separation zone to return slurry of a given concentration of catalyst to the reaction zone. It will also be apparent that injection of gaseous material into the slurry in ac cordance with my invention, brings about a denite improvement in allowable concentration of catalyst in slurry.

In order to provide a better understanding of this invention, reference will be had to the accompanying drawing which illustrates a preferred embodiment thereof.

In the drawing, vaporized naphtha feed oil having an API gravity of 56.3 enters through line 1 at the rate of 12,780 b. p. s. d. and a temperature of 995 F. The vaporous feed enters reactor 3 through line 4 together with hydrogen containing recycle gas supplied through line 2 at the rate of 4,400 s. c. ./b. b. l. and a temperature of l200 F. In reactor 3, the reactant vapors are contacted with a uidized bed of finely divided molybdenum trioxide on alumina catalyst, containing 9% by weight of molybdenum trioxide, at an average reaction temperature of 910 F., a reaction pressure of 250 p. s. i. g., a catalyst to oil ratio of about 1.4 and a weight space velocity of 0.7. drawn from the dense phase of reactor 3 and passed to stripper 5 through line 6 by means of lift gas supplied through line 7. In stripper 5, the catalyst is stripped by stripping gas, e. g., steam, admitted through line 8. From the dense phase of stripper 5,r catalyst is withdrawn through line 9 and passed to a regeneration zone (not shown). Regenerated catalyst is introduced to reactor 3 through line 10. Gases from the dilute upper phase of stripper 5 are returned to reactor 3 through line 11.

The vaporous reaction product is passed through cyclone separator 12 where the majority of the entrained catalyst is removed and returned to the dense phase of reactor 3 through line 13.

Vaporous reaction product consisting of normally gaseous material, gasoline, polymer and entrained catalyst lines leaves the cyclone separator 12 and is passed to fractionator 15 through line 14. Fractionator 15 is operated at a pressure of 240 p. s. i. g. In fractionator 15, polymer and part of the gasoline is condensed from the reaction product. This'is eifected by upwardly owing Vaporous product being countercurrently contacted with downwardly owing polymer. Liquid polymer and catalyst nes are withdrawn from the bottom of fractionator 15 and passed through line 16 to pump 17. From pump 17 a portion of the mixture of polymer and catalyst fines is returned to the upper part of fractionator 15 through line 18 and cooler 37, and the remaining Catalyst is continuously with.`

, 6 Y portion is passed to settler 19 through line 20., Flush oil for pump 17 is obtained from the upper portion of fractionator 15 by means of line 21pumpA 22, and line 23. In settler 19, catalyst nes settle out of the liquid polymer to form a slurry in the lower part of said zone while a' layerof supernatant liquid polymer of substantially reduced catalyst nes content forms in the upper part of said zone. Settler 19'is maintained at a pressure of 280 p. s. i. g. 283 b. p. s. d. of'raw polymer product with an API gravity of 35.0 is withdrawn from settler 19 through line 24. A slurry of 'catalyst i'lnes and polymer containing 1.5 lb. of catalyst lines per gallon of polymer is withdrawn from the bottom of settler 19' through pressure reducing valve 36, and line 25 into line 26 where recycle gas obtained from linev 40 is injected Vaporous reaction product passes from the top of frac- I tionator 15 through line 27 and cooler 38 into separator 28 where raw gasoline is condensed and the normally gaseous products are separated. Raw gasoline is Withdrawn from separator 28 through line 29 to pump 30.

From pump 30, 11,450 b. p. s. d. of raw gasoline having an API gravity of 54.4 pass out through line 31 and an equal amount of said gasoline is returned to fractionator 15 through line 32. Normally gaseous products are withdrawn from separator 28 through line 33. A portion of said gaseous products is passed through line 34 to pump 35 and is recycled to the process through line 2. The remainder of said gaseous products constitutes the net gas production of the process.

In the foregoing description of a preferred embodiment of my invention, certain conventionalpequipment such as heat exchangers', valves, furnaces, etc., has not been shown. Such equipment can be easily supplied as required by anyone familiar with they art and my disclosure should be read as including such conventional equipment as may be convenient or necessary.

I claim:

1. A hydroforming process which comprises contacting hydrocarbon oil with a dense fluid bed of nely divided hydroforming catalyst under suitable hydroforming conditions in a reaction zone to produce a vaporous reaction product containing normally gaseous material, gasoline, polymer and entrained catalyst fines, separating polymer from said reaction product, separating normally gaseous material from said reaction product, scrubbing fines from the reaction product with polymer, separating polymer containing catalyst fines from the bulk of the polymer in a settling zone maintained at a pressure of between about 15 and about 35 p. s. i. greater than the pressure maintained in the reaction zone, injecting a portion of said separated normally gaseous material into said slurryyand passing said slurry of catalyst lines and gaseous material to the reaction zone.

2. A hydroforming process which comprises contacting a vaporized naphtha feed with a dense iluid bed of nely divided catalyst comprising molybdenum trioxide supported on alumina at a pressure of about 50 to about 500 p. s. i. g., a temperature of about 850 to about 950 F., a catalyst to oil ratio of about 0.1 to about 2.0, a weight space velocity of about 0.1 to about 2.5 in the presence of added hydrogen in the amount of about 1000 to about 7500 s. c. f. b., thereby producing a vaporous reaction product containing normally gaseous material, gasoline, polymer and entrained catalyst iines, separating polymer from said reaction product, scrubbing ines from the reaction product with polymer, separating normally gaseous material from the reaction product, separating polymer containing catalyst fines from the bulk of the polymer in a settling zone maintained at a pressure of about l5 to about 35 p. s. i. greater than the material intoA saidslurry of nes AinV an amount of about 21o-about 5 s. c. f. 'of .thelgaseousrmaterial.perlb, ofv 5 slurry, Vpassing theslurry, of fines and gaseousmaterial to a transfer zone Wherein'Athe linearyelocityis about 1G to about 50 it. `per sec., recycling. the gaseous material@y and slurry from the" transfer zone V to the reactionl zone,

andvrecyclingV anothe'rrportion ofv normally* gaseous ma-A 19` terial to .the' reaction zone. A

3. 'A process which vcomprises,contacting hydrocarbon oil witlila "dense 4iuid` bed lof finely divided; Catalyst in@ reaction` zone to produce a yaporous realvtion,productl Containing normally.' gaseous ,`.1,11at .:ria1,gasolinap polymen 15. andutranes .catalyst .'nesfeparatina polymer .frOm Y said.,V react/ion Aproduct', separatingmormally gaseous ma-` terial ,from .Said Areaction Producti,,scrubbingQnes v from. the` reaction product with ,pqlymeneparating polymer:- containing catalyst nesgirom thabulk of thepolymer lin.

a settling zone mantand'ata pressureofbetween. about.v 15 and 4abo'utS p. ,s. i. greaterfthan theA pressure main-y tainedjngthe reactionvvz'one; .injegtinga portion of vsaid separated,l normally 4 gaseous -rnaterialv into said slurry, and ,passing SaidV slurry, ofcatalyst nes` and gaseous ma,

terial to thesreation zone.

References Cited in the levof this patent UNITED STATES PATENTS f 

2. A HYDROFORMING PROCESS WHICH COMPRISES CONTACTING A VAPORIZED NAPHTHA FEED WITH A DENSE FLUID BED OF FINELY DIVIDED CATALYST COMPRISING MOLYBDENUM TRIOXIDE SUPPORTED ON ALUMINA AT A PRESSURE OF ABOUT 850 TO ABOUT 500 P. S. I. G., A TEMPERATURE OF ABOUT 850 TO ABOUT 950*F., A CATALYST TO OIL RATIO OF ABOUT 0.1 TO ABOUT 2.0, A WEIGHT SPACE VELOCITY OF ABOUT 0.1 TO ABOUT 2.5 IN THE PRESENCE OF ADDED HYDROGEN IN THE AMOUNT OF ABOUT 1000 TO ABOUT 7500 S. C. F. B., THEREBY PRODUCING A VAPOROUS REACTION PRODUCT CONTAINING NORMALLY GASEOUS MATERIAL, GASOLINE, POLYMER AND ENTRAINED CATALYST FINES, SEPARATING POLYMER FROM SAID REACTION PRODUCT, SCRUBBING FINES FROM THE REACTION PRODUCT WITH POLYMER, SEPARATING NORMALLY GASEOUS MATERIAL FROM THE REACTION PRODUCT, SEPARATING POLYMER CONTAINING CATALYST FINES FROM THE BULK OF THE POLYMER IN A SETTLING ZONE MAINTAINED AT A PRESSURE OF ABOUT 15 TO ABOUT 35 P. S. I. GREATER THAN THE PRESSURE MAINTAINED IN THE REACTION ZONE TO FORM A SLURRY CONTAINING ABOUT 1.0 TO ABOUT 2.5 LB. OF CATALYST PER GALLON OF OIL VEHICLE, INJECTING A PORTION OF THE GASEOUS MATERIAL INTO SAID SLURRY OF FINES IN AN AMOUNT OF ABOUT 2 TO ABOUT 5 S. C. F. OF THE GASEOUS MATERIAL PER LB. OF SLURRY, PASSING THE SLURRY OF FINES AND GASEOUS MATERIAL TO A TRANSFER ZONE WHEREIN THE LINEAR VELOCITY IS ABOUT 10 TO ABOUT 50 FT. PER SEC. RECYCLING THE GASEOUS MATERIAL AND SLURRY FROM THE TRANSFER ZONE TO THE REACTION ZONE, AND RECYCLING ANOTHER PORTION OF NORMALLY GASEOUS MATERIAL TO THE REACTION ZONE. 